| Title: | "Characteristics of ambient ammonia and its effects on particulate ammonium in winter of urban Beijing, China" |
| Author(s): | Zhang R; Han Y; Shi A; Sun X; Yan X; Huang Y; Wang Y; |
| Address: | "National Engineering Research Center of Urban Environmental Pollution Control, Beijing Key Laboratory of Urban Atmospheric Volatile Organic Compounds Pollution Control and Application, Municipal Research Institute of Environmental Protection, Beijing, 100037, China. National Engineering Research Center of Urban Environmental Pollution Control, Beijing Key Laboratory of Urban Atmospheric Volatile Organic Compounds Pollution Control and Application, Municipal Research Institute of Environmental Protection, Beijing, 100037, China. sunxuesong@cee.cn" |
| Journal Title: | Environ Sci Pollut Res Int |
| DOI: | 10.1007/s11356-021-14108-w |
| ISSN/ISBN: | 1614-7499 (Electronic) 0944-1344 (Linking) |
| Abstract: | "To understand the characteristics of winter fine aerosol pollution in Beijing, we conducted continuous measurements of the atmospheric trace gas ammonia (NH(3)), PM(2.5), and inorganic ions in PM(2.5) at an urban site in Beijing from February 13 to March 17, 2015. The hourly average concentration of NH(3) throughout the campaign was 15.4 +/- 17.5 ppb. NH(3) concentrations correlated well with NH(4)(+) in PM(2.5), indicating the dominant precursor role of NH(3) on NH(4)(+) formation. The diurnal profile indicated an increase in NH(3) concentrations during the morning rush hours, which was likely due to vehicle emissions. The mean ammonium conversion ratio (NHR) was 0.26, with the highest value of 0.32 in the afternoon. Elevated NHR, nitrate oxidation ratio (NOR), and NH(4)(+) coincided with the significant increase in O(3) levels in the afternoon, indicating the large daytime formation of NH(4)NO(3) via photochemical reactions. Moreover, higher NHR values occurred under higher relative humidity (RH >60%) and lower temperature (0-10 degrees C). NHR increased during the nighttime and correlated well with RH, indicating the dominant role of heterogeneous reactions on gas-particle partitioning. The sulfate oxidation ratio (SOR) and NOR showed positive correlations with RH, which suggests that the conversions of SO(2) to SO(4)(2-) and NO(2) to NO(3)(-) were sensitive to changes in RH. The sustained increase in SO(4)(2-) concentrations at RH >60% suggests that RH had a higher influence on SO(4)(2-) formation than on NO(3)(-) formation. As the sole precursor of NH(4)(+), NH(3) significantly enhanced daytime NH(4)NO(3) formation via homogeneous gas-phase reactions and also promoted sulfate formation via both homogeneous and heterogeneous reactions. Moreover, the back trajectory results inferred a high contribution of southwestern air masses to atmospheric NH(3) and NH(4)(+) aerosol variations in Beijing. The result suggests the need for controlling the vehicle emissions to reduce the high levels of NH(3) and alleviate PM(2.5) pollution in winter in Beijing" |
| Keywords: | Aerosols/analysis *Air Pollutants/analysis Ammonia *Ammonium Compounds/analysis Beijing China Environmental Monitoring Particulate Matter/analysis Seasons Ammonium Gas-to-particle conversion Nhr Regional transport Urban Beijing; |
| Notes: | "MedlineZhang, Rui Han, Yuhua Shi, Aijun Sun, Xuesong Yan, Xiao Huang, Yuhu Wang, Yu eng 41303074/National Natural Science Foundation of China/ Germany 2021/07/05 Environ Sci Pollut Res Int. 2021 Nov; 28(44):62828-62838. doi: 10.1007/s11356-021-14108-w. Epub 2021 Jul 3" |
